Smartcard encryption cycling

ABSTRACT

Various arrangements for encrypting multiple television channels are presented. A first television channel of a plurality of television channels to be protected via a first entitlement control message (ECM) using a first encryption scheme may be designated. The plurality of television channels may be transmitted using a single transponder stream. A second television channel of the plurality of television channels to be protected via a second ECM encrypted using a second encryption scheme while the first television channel of the plurality of television channels is protected using the first encryption scheme may be designated. The first and second ECMs may be transmitted to a plurality of television receivers. Data from the first ECM may be used for descrambling of the first television channel by the plurality of television receivers. Data from the second ECM may be used for descrambling of the second television channel by the plurality of television receivers.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/828,001, filed Mar. 14, 2013, entitled “Smartcard Encryption Cycling,which claims priority to U.S. provisional application 61/611,483, filedMar. 15, 2012, entitled “Reception, Recording, Storage, and Manipulationof Multiple Television Channels, the entire disclosure of which ishereby incorporated by reference for all purposes.

U.S. application Ser. No. 13/828,001 also claims priority to U.S.provisional application 61/745,710, filed Dec. 24, 2012, entitled“Smartcard Encryption Cycling,” the entire disclosure of which is herebyincorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

A television viewer may desire to watch and/or record multipletelevision channels at the same time. For instance, during weekdayprimetime, many television programs may be broadcast simultaneously ondifferent television channels that the television viewer desires toeither watch live or store for later viewing. For many cable andsatellite television distribution systems, a set-top box may be used toreceive, store, and display television channels on a television (orother form of display device). Such set-top boxes may have limitedcapabilities to concurrently display and/or store multiple televisionchannels at the same time.

SUMMARY

In some embodiments, a system for encrypting multiple televisionchannels, is presented. The system may include one or more processors.The system may include a memory communicatively coupled with andreadable by the one or more processors and having stored thereinprocessor-readable instructions. When executed by the one or moreprocessors, the instructions may cause the one or more processors todesignate a first television channel of a plurality of televisionchannels to be protected via a first entitlement control message using afirst encryption scheme. The plurality of television channels may betransmitted using a single transponder stream. The instructions maycause the one or more processors to designate a second televisionchannel of the plurality of television channels to be protected via asecond entitlement control message encrypted using a second encryptionscheme while the first television channel of the plurality of televisionchannels is protected using the first encryption scheme. Theinstructions may cause the one or more processors to cause the firstentitlement control message encrypted using the first encryption schemeand a second entitlement control message encrypted using the secondencryption scheme to be transmitted to a plurality of televisionreceivers. Data from the first entitlement control message may be usedfor descrambling of the first television channel by the plurality oftelevision receivers. Data from the second entitlement control messagemay be used for descrambling of the second television channel by theplurality of television receivers.

Embodiments of such a system may include one or more of the following:The first entitlement control message encrypted using the firstencryption scheme may require more processing by a television receiverof the plurality of television receivers to decrypt than the secondentitlement control message encrypted using the second encryptionscheme. The instructions may cause the one or more processors to causethe plurality of channels to be transmitted concurrently to a pluralityof television receivers using the single transponder stream. Data fromthe first entitlement control message may be required to descramble thefirst television channel. Data from the second entitlement controlmessage may be required to concurrently descramble the second televisionchannel during a time period the first television channel is beingdescrambled. At a given time, only one television channel of theplurality of television channels transmitted concurrently using thesingle transponder stream may be protected using the first encryptionscheme. The system may include a television receiver comprising asmartcard, the television receiver configured to decrypt the firstentitlement control message, wherein the television receiver is of theplurality of television receivers. The television receiver may beconfigured to decrypt the second entitlement control message. Thetelevision receiver may be configured to descramble the first televisionchannel using data from the first entitlement control message. Thetelevision receiver may be configured to descramble the secondtelevision channel using data from the second entitlement controlmessage concurrently while descrambling the first television channelusing data from the first entitlement control message.

Additionally or alternatively, embodiments of such a system may includeone or more of the following: The television receiver being configuredto decrypt the first entitlement control message may take a longerperiod of time to process than decrypting the second entitlement controlmessage. The instructions may cause the one or more processors to, afterthe television service provider has transmitted the first entitlementcontrol message and the second entitlement control message: designatethe first television channel of the plurality of television channels tobe protected via a third entitlement control message encrypted using thesecond encryption scheme; designate the second television channel of theplurality of television channels to be protected via a fourthentitlement control message encrypted using the first encryption schemewhile the first television channel of the plurality of televisionchannels is protected using the second encryption scheme; and cause thethird entitlement control message encrypted using the second encryptionscheme and the fourth entitlement control message encrypted using thefirst encryption scheme to be transmitted. The third entitlement controlmessage may be used for decryption of the first television channel. Thefourth entitlement control message may be used for decryption of thesecond television channel.

In some embodiments, a method for encrypting multiple televisionchannels is presented. The method may include designating, by thetelevision service provider system, a first television channel of aplurality of television channels to be protected via a first entitlementcontrol message using a first encryption scheme. The plurality oftelevision channels may be transmitted using a single transponderstream. The method may include designating, by the television serviceprovider system, a second television channel of the plurality oftelevision channels to be protected via a second entitlement controlmessage encrypted using a second encryption scheme while the firsttelevision channel of the plurality of television channels is protectedusing the first encryption scheme. The method may include transmitting,by the television service provider system, the first entitlement controlmessage encrypted using the first encryption scheme and a secondentitlement control message encrypted using the second encryption schemeto a plurality of television receivers. Data from the first entitlementcontrol message may be used for descrambling of the first televisionchannel by the plurality of television receivers. Data from the secondentitlement control message may be used for descrambling of the secondtelevision channel by the plurality of television receivers.

Embodiments of such a method may include one or more of the following:The first entitlement control message encrypted using the firstencryption scheme may require more processing by a television receiverof the plurality of television receivers to decrypt than the secondentitlement control message encrypted using the second encryptionscheme. The method may include transmitting, by the television serviceprovider system, the plurality of channels concurrently to a pluralityof television receivers using the single transponder stream. Data fromthe first entitlement control message may be required to descramble thefirst television channel. Data from the second entitlement controlmessage may be required to concurrently descramble the second televisionchannel during a time period the first television channel is beingdescrambled. At a given time, only one television channel of theplurality of television channels transmitted concurrently using thesingle transponder stream may be protected using the first encryptionscheme.

The method may include decrypting, by a smartcard of a televisionreceiver, the first entitlement control message, wherein the televisionreceiver is of the plurality of television receivers. The method mayinclude decrypting, by the smartcard of the television receiver, thesecond entitlement control message. The method may include descrambling,by the television receiver, the first television channel using data fromthe first entitlement control message. The method may includedescrambling, by the television receiver, the second television channelusing data from the second entitlement control message concurrentlywhile descrambling the first television channel using data from thefirst entitlement control message. Decrypting, by the smartcard of thetelevision receiver, the first entitlement control message may take alonger period of time than decrypting the second entitlement controlmessage. The method may include, after the television service providerhas transmitted the first entitlement control message and the secondentitlement control message: designating, by the television serviceprovider system, the first television channel of the plurality oftelevision channels to be protected via a third entitlement controlmessage encrypted using the second encryption scheme; designating, bythe television service provider system, the second television channel ofthe plurality of television channels to be protected via a fourthentitlement control message encrypted using the first encryption schemewhile the first television channel of the plurality of televisionchannels is protected using the second encryption scheme; andtransmitting, by the television service provider system, the thirdentitlement control message encrypted using the second encryption schemeand the fourth entitlement control message encrypted using the firstencryption scheme. The third entitlement control message may be used fordecryption of the first television channel. The fourth entitlementcontrol message may be used for decryption of the second televisionchannel.

In some embodiments, a non-transitory processor-readable medium forencrypting multiple television channels is presented. The non-transitoryprocessor-readable medium may include processor-readable instructionsconfigured to cause one or more processors to designate a firsttelevision channel of a plurality of television channels to be protectedvia a first entitlement control message using a first encryption scheme.The plurality of television channels may be transmitted using a singletransponder stream. The instructions may be configured to cause one ormore processors to designate a second television channel of theplurality of television channels to be protected via a secondentitlement control message encrypted using a second encryption schemewhile the first television channel of the plurality of televisionchannels is protected using the first encryption scheme. Theinstructions may be configured to cause one or more processors to causethe first entitlement control message encrypted using the firstencryption scheme and a second entitlement control message encryptedusing the second encryption scheme to be transmitted to a plurality oftelevision receivers. Data from the first entitlement control messagemay be used for descrambling of the first television channel by theplurality of television receivers. Data from the second entitlementcontrol message may be used for descrambling of the second televisionchannel by the plurality of television receivers.

Embodiments of such a non-transitory processor-readable medium mayinclude one or more of the following: The first entitlement controlmessage encrypted using the first encryption scheme may require moreprocessing by a television receiver of the plurality of televisionreceivers to decrypt than the second entitlement control messageencrypted using the second encryption scheme. The instructions may beconfigured to cause one or more processors to cause the plurality ofchannels to be transmitted concurrently to a plurality of televisionreceivers using the single transponder stream. Data from the firstentitlement control message may be required to descramble the firsttelevision channel. Data from the second entitlement control message maybe required to concurrently descramble the second television channelduring a time period the first television channel is being descrambled.At a given time, only one television channel of the plurality oftelevision channels transmitted concurrently using the singletransponder stream may be protected using the first encryption scheme.The instructions may be configured to cause one or more processors to,after the television service provider has transmitted the firstentitlement control message and the second entitlement control message:designate the first television channel of the plurality of televisionchannels to be protected via a third entitlement control messageencrypted using the second encryption scheme; designate the secondtelevision channel of the plurality of television channels to beprotected via a fourth entitlement control message encrypted using thefirst encryption scheme while the first television channel of theplurality of television channels is protected using the secondencryption scheme; and cause the third entitlement control messageencrypted using the second encryption scheme and the fourth entitlementcontrol message encrypted using the first encryption scheme to betransmitted. The third entitlement control message may be used fordecryption of the first television channel. The fourth entitlementcontrol message may be used for decryption of the second televisionchannel.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of embodiments of the invention may be realizedby reference to the following figures. In the appended figures, similarcomponents or features may have the same reference label. Further,various components of the same type may be distinguished by followingthe reference label by a dash and a second label that distinguishesamong the similar components. If only the first reference label is usedin the specification, the description is applicable to any one of thesimilar components having the same first reference label irrespective ofthe second reference label.

FIG. 1 illustrates an embodiment of a satellite television distributionsystem.

FIG. 2 illustrates an embodiment of a set-top box (STB).

FIG. 3 illustrates an embodiment of a television service providerencryption system.

FIG. 4 illustrates an embodiment of a data transmission and encryptionfor satellite television channel distribution.

FIG. 5 illustrates an embodiment of multiple encryption schemescorresponding to multiple television channels.

FIG. 6 illustrates another embodiment of multiple encryption schemescorresponding to multiple television channels.

FIG. 7 illustrates an embodiment of a method for using multipleencryption schemes for encryption of entitlement control messages (ECMs)within a single transponder stream.

FIG. 8 illustrates an embodiment of a method for receiving multipletelevision channels corresponding to ECMs encrypted using multipleencryption schemes within a single transponder stream.

FIG. 9 illustrates an embodiment of a computer system.

DETAILED DESCRIPTION

In some situations, a user (e.g., a television service subscriber) maydesire to watch and/or record multiple television channels concurrently.For example, while the user is watching a first television program on afirst television channel, the user may be recording a second televisionprogram on a second television channel using a digital video recorder(DVR). As such, the second television program may be available forpresentation to the user (or someone else) at a later time. In somesituations, rather than a user desiring to watch and/or record twotelevision channels at a given time, three or more television channelsmay be watched and/or recorded simultaneously (e.g., one televisionchannel may be watched while three others are concurrently recorded).Such a situation may be common in a household where multiple personseach desire to watch different television programs broadcastsimultaneously. While in an ideal situation it may be possible to watchand/or record every available television channel concurrently, alimiting factor may be the television service receiving equipment. Forinstance, for many television service providers, a set top box (STB) isnecessary to decrypt and/or decode television channels (and/or otherrelated television services) from the television service provider forstorage and/or presentation via a presentation device (e.g., atelevision). Such a STB may only be able to tune to and/or decode afinite number of television channels simultaneously.

In order to control access to television channels distributed by thetelevision service provider, television channels may be protected by thetelevision service provider to prevent non-subscribers from acquiringunauthorized (e.g., free) access. In some embodiments, to accomplishthis goal, STBs contain a smartcard that is used to decrypt entitlementcontrol messages. An entitlement control message may contain data(possibly referred to as a control word (CW)), that is used todescramble television channels. As such, to descramble a televisionchannel using a control word, the control word may need to be obtainedfrom a corresponding ECM. An ECM may be encrypted and may need to bedecrypted to obtain one or more CWs from the ECM. These CWs may then beused to descramble one or more television channels.

A smartcard may have a finite ability to decrypt ECMs. Such a finiteability may be due to the smartcard's processing power and/or otherlimits on the ability of the smartcard to decrypt multiple ECMs during agiven time period. Such a finite ability may not be an issue when asingle television channel is tuned to by a STB. However, if a user isattempting to view and/or record multiple television channelssimultaneously, the number of ECMs requiring decryption during a giventime period may increase. For instance, in some embodiments, eachtelevision channel is associated with its own ECMs. Therefore, for agiven time period, a different ECM may need to be decrypted for eachtelevision channel being received for presentation and/or recording. Insome embodiments, a new ECM is decrypted for a television channel everyten seconds. If the STB is receiving five television channels, this maymean that five different ECMs are to be decrypted every ten seconds.

While it may be possible to use multiple smartcards or a smartcard withincreased processing power to increase the number of ECMs that can bedecrypted over a given time period, it may be worthwhile, such as forcost concerns, to use a smartcard with limited abilities to decryptECMs. In order to increase the number of television channels that can besimultaneously stored and/or recorded, the number of ECMs that can bedecrypted over a given time period may need to be increased.

It should be understood that data may be received by a STB from atelevision service provider in the form of one or more transponderstreams; as such “simultaneously” or “concurrently” storing and/orrecording multiple television channels may refer to over a given periodof time performing such functions for multiple television channels. Forexample, simultaneously or concurrently recording two televisionchannels refers to performing functions related to recording twotelevision channels transmitted during the same time period (e.g., 8:00PM-8:30 PM). During this time period, ECMs may need to be decrypted foreach of the multiple television channels in order for the televisionchannels to be simultaneously or concurrent presented and/or recorded.

Instead of each television channel being protected via an ECM encryptedusing the same encryption scheme, one or more television channels may beprotected via ECMs encrypted using a higher level of encryption(referred to as “heavy” encryption) than other television channels. AnECM encrypted using heavy encryption may require more processing todecode by a STB's smartcard than an ECM encrypted using a lower level ofencryption (referred to as “light” encryption). To enable a smartcard todecode ECMs related to multiple channels desired to be decoded forstorage and/or viewing simultaneously, television channels may beprotected by ECMs encrypted using light encryption. Such light encryptedECMs may be more quickly (e.g., requiring less processing) decrypted bya STB's decryption smartcard. Some number of television channels may beprotected by ECMs encrypted using heavy encryption that require longer(e.g., requiring more processing) to be decrypted by the decryptionsmartcard. A smartcard may be able to handle decryption for a givennumber of television channels protected by “heavy” encrypted ECMs and by“light” encrypted ECMs concurrently. As such, if only a limited numberof television channels (e.g., one) are being received for recordingand/or presentation, at a given time, is protected using heavyencryption, a smartcard may be able to handle decryption of the ECMs formultiple television channels due to the majority of television channelsbeing protected by ECMs with “light” encryption (which require lessprocessing for the smartcard to decrypt).

Which one or more television channels are protected by ECMs encryptedusing heavy and light encryption may rotate. For example, on aparticular transponder used to transmit a transponder stream containingmultiple television channels, at a given time one of the televisionchannels may be protected by an ECM encrypted using heavy encryption.Each other television channel in the transponder stream at the giventime may be protected by ECMs encrypted using light encryption. After apredefined period of time, the television channels protected by an ECMencrypted using heavy encryption may rotate. As such, at any given time,in this example, only a single television channel transmitted in thetransponder stream may be protected by an ECM encrypted using heavyencryption. Therefore, at a STB receiving at least some of the multipletelevision channels, a smartcard may only need to decrypt one ECMencrypted using heavy encryption (with the other ECMs encrypted usinglight encryption) over a given period of time, thus allowing thesmartcard to decode all required ECMs in a timely manner.

Rotating which television channels out of a group of television channelsis protected by an ECM encrypted using heavy or light encryption may besufficient to protect all of the television channels. For instance,while a non-subscriber (e.g., a person making unauthorized access to thetelevision service provider's network) may have equipment sufficient tocrack the light encryption, the equipment may not be sufficient to crackthe heavy encryption in a timely manner. If, for example, ten seconds ofa television channel transmitted by the television service provider isprotected by a heavy encrypted ECM (with the remainder of the time beingprotected by a light encrypted ECM), the television channel may berendered unenjoyable to the non-subscriber because 10 seconds of eachminute of the television channel's audio and/or video would be unable tobe descrambled, thus ruining the non-subscribers viewing/listeningexperience. Since each of the television channels would have a tensecond chunk each minute protected by a heavy encrypted ECM, each of thetelevision channels may be rendered unenjoyable to the non-subscriber.

Such arrangements may be especially useful when multiple televisionchannels are to be watched and/or recorded from a single transponderstream. For instance, a television service provider may group televisionchannels that are likely to be desired by users to be watched and/orrecorded concurrently onto a single transponder stream. For instance, asingle transponder stream may be used to carry each of the majortelevision networks (e.g., ABC, CBS, NBC, and FOX). A single tuner of aSTB may be used to simultaneously receive each of the televisionchannels transmitted in the same transponder stream. The televisionservice provider may rotate which of the television channel channels inthe transponder stream are protected by an ECM encrypted by heavy andlight encryption.

FIG. 1 illustrates an embodiment of a satellite television distributionsystem 100. Satellite television distribution system 100 may include:television service provider system 110, satellite transmitter equipment120, satellites 130, satellite dish 140, set-top box 150, and television160. Alternate embodiments of satellite television distribution system100 may include fewer or greater numbers of components. While only onesatellite dish 140, set-top box 150, and television 160 (collectivelyreferred to as “user equipment”) are illustrated, it should beunderstood that multiple (e.g., tens, thousands, millions) instances ofuser equipment may receive television signals from satellites 130.

Television service provider system 110 and satellite transmitterequipment 120 may be operated by a television service provider. Atelevision service provider may distribute television channels,on-demand programming, programming information, and/or other services tousers. Television service provider system 110 may receive feeds of oneor more television channels from various sources. Such televisionchannels may include multiple television channels that contain the samecontent (but may be in different formats, such as high-definition andstandard-definition). To distribute such television channels to users,feeds of the television channels may be relayed to user equipment viaone or more satellites via transponder streams. Satellite transmitterequipment 120 may be used to transmit a feed of one or more televisionchannels from television service provider system 110 to one or moresatellites 130. While a single television service provider system 110and satellite transmitter equipment 120 are illustrated as part ofsatellite television distribution system 100, it should be understoodthat multiple instances of transmitter equipment may be used, possiblyscattered geographically to communicate with satellites 130. Suchmultiple instances satellite transmitting equipment may communicate withthe same or with different satellites. Different television channels maybe transmitted to satellites 130 from different instances oftransmitting equipment. For instance, a different satellite dish oftransmitting equipment 120 may be used for communication with satellitesin different orbital slots.

Satellites 130 may be configured to receive signals, such as transponderstreams of television channels, from one or more satellite uplinks suchas satellite transmitter equipment 120. Satellites 130 may relayreceived signals from satellite transmitter equipment 120 (and/or othersatellite transmitter equipment) to multiple instances of user equipmentvia transponder streams. Different frequencies may be used for uplinktransponder streams 170 from transponder stream 180. Satellites 130 maybe in geosynchronous orbit. Each satellite 130 may be in a differentorbital slot, such that the signal path between each satellite, uplinkstations, and user equipment vary. Multiple satellites 130 may be usedto relay television channels from television service provider system 110to satellite dish 140. Different television channels may be carriedusing different satellites. Different television channels may also becarried using different transponders of the same satellite; thus, suchtelevision channels may be transmitted at different frequencies and/ordifferent frequency ranges. As an example, a first and second televisionchannel may be carried on a first transponder of satellite 130-1. Athird, fourth, and fifth television channel may be carried using adifferent satellite or a different transponder of the same satelliterelaying the transponder stream at a different frequency. A transponderstream transmitted by a particular transponder of a particular satellitemay include a finite number of television channels, such as seven.Accordingly, if many television channels are to be made available forviewing and recording, multiple transponder streams may be necessary totransmit all of the television channels to the instances of userequipment.

Satellite dish 140 may be a piece of user equipment that is used toreceive transponder streams from one or more satellites, such assatellites 130. Satellite dish 140 may be provided to a user for use ona subscription basis to receive television channels provided by thetelevision service provider system 110, satellite uplink 120, and/orsatellites 130. Satellite dish 140 may be configured to receivetransponder streams from multiple satellites and/or multipletransponders of the same satellite. Satellite dish 140 may be configuredto receive television channels via transponder streams on multiplefrequencies. Based on the characteristics of set-top box (STB) 150and/or satellite dish 140, it may only be possible to capturetransponder streams from a limited number of transponders concurrently.For example, a tuner of STB 150 may only be able to tune to a singletransponder stream from a transponder of a single satellite at a time.

In communication with satellite dish 140, may be one or more sets ofreceiving equipment. Receiving equipment may be configured to decodesignals received from satellites 130 via satellite dish 140 for displayon a display device, such as television 160. Receiving equipment may beincorporated as part of a television or may be part of a separatedevice, commonly referred to as a set-top box (STB). Receiving equipmentmay include a satellite tuner configured to receive television channelsvia a satellite. In FIG. 1, receiving equipment is present in the formof set-top box 150. As such, set-top box 150 may decode signals receivedvia satellite dish 140 and provide an output to television 160. FIG. 2provides additional detail of receiving equipment.

Television 160 may be used to present video and/or audio decoded byset-top box 150. Set-top box 150 may also output a display of one ormore interfaces to television 160, such as an electronic programmingguide (EPG). In some embodiments, a display device other than atelevision may be used.

Uplink transponder stream 170-1 represents a signal between satelliteuplink 120 and satellite 130-1. Uplink transponder stream 170-2represents a signal between satellite uplink 120 and satellite 130-2.Each of uplink transponder streams 170 may contain streams of one ormore different television channels. For example, uplink transponderstream 170-1 may contain a certain group of television channels, whileuplink transponder stream 170-2 contains a different grouping oftelevision channels. Each of these television channels may be scrambledsuch that unauthorized persons are prevented from accessing thetelevision channels.

Transponder stream 180-1 represents a signal between satellite 130-1 andsatellite dish 140. Transponder stream 180-2 represents a signal pathbetween satellite 130-2 and satellite dish 140. Each of transponderstreams 180 may contain one or more different television channels in theform of transponder streams, which may be at least partially scrambled.For example, transponder stream 180-1 may include a first transponderstream containing a first group of television channels, whiletransponder stream 180-2 may include a second transponder streamcontaining a different group of television channels. A satellite maytransmit multiple transponder streams to user equipment. For example, atypical satellite may relay 32 transponder streams via correspondingtransponders to user equipment. Further, spot beams are possible. Forexample, a satellite may be able to transmit a transponder stream to aparticular geographic region (e.g., to distribute local televisionchannels to the relevant market). Different television channels may betransmitted using the same frequency of the transponder stream to adifferent geographic region.

FIG. 1 illustrates transponder stream 180-1 and transponder stream 180-2being received by satellite dish 140. For a first group of televisionchannels, satellite dish 140 may receive a transponder stream oftransponder stream 180-1; for a second group of channels, a transponderstream of transponder stream 180-2 may be received. STB 150 may decodethe received transponder stream. As such, depending on which televisionchannel(s) are desired, a transponder stream from a different satellite(or a different transponder of the same satellite) may be accessed anddecoded by STB 150. Further, while two satellites are present insatellite television distribution system 100, in other embodimentsgreater or fewer numbers of satellites may be present for receiving andtransmitting transponder streams to user equipment.

Network 190 may serve as a secondary communication channel betweentelevision service provider system 110 and set-top box 150. Via such asecondary communication channel, bidirectional exchange of data mayoccur. As such, data may be transmitted to television service providersystem 110 via network 190. Data may also be transmitted from televisionservice provider system 110 to STB 150 via network 190. Network 190 maybe the Internet. While audio and video services may be provided to STB150 via satellites 130, feedback from STB 150 to television serviceprovider system 110 may be transmitted via network 190.

FIG. 1 illustrates an example of a satellite-based television channeldistribution system. It should be understood that at least some of theaspects of such a system may be similar to a cable televisiondistribution system. For example, in a cable television system, ratherthan using satellite transponders, multiple RF channels on a cable maybe used to transmit streams of television channels. As such, aspectsdetailed herein may be applicable to cable television distributionsystems.

FIG. 2 illustrates a block diagram of an embodiment of a set-top box200. STB 200 may be set-top box 150 of FIG. 1, or may be incorporated aspart of a television, such as television 160 of FIG. 1. STB 200 mayinclude: processors 210, tuners 215, network interface 220,non-transitory computer-readable storage medium 225, electronicprogramming guide (EPG) 230, television interface 235, networkinginformation table (NIT) 240, digital video recorder (DVR) 245, userinterface 250, demultiplexer 255, smart card 260, and/or descramblingengine 265. In other embodiments of STB 200, fewer or greater numbers ofcomponents may be present. It should be understood that the variouscomponents of STB 200 may be implemented using hardware, firmware,software, and/or some combination thereof. For example, EPG 230 may beexecuted by processors 210.

FIG. 2 illustrates an embodiment of STB 200, which may typically be inthe form of a separate device configured to be connected with apresentation device, such as a television. Embodiments of STB 200 mayalso be referred to as a “television receiver.” In addition to being inthe form of an STB, a television receiver may be incorporated intoanother device, such as a television. For example, a television may havean integrated television receiver (which does not involve an externalSTB being coupled with the television). A television receiver maycontain some or all of the components of STB 200 and/or may be able toperform some or all of the functions of STB 200. Accordingly, instancesin this document referring to an STB and steps being performed by an STBmay also be performed, more generally, by a television receiver.

Processors 210 may include one or more general-purpose processorsconfigured to perform processes such as tuning to a particular channel,displaying the EPG, and/or receiving and processing input from a user.Processors 210 may include one or more special purpose processors. Forexample, processors 210 may include one or more processors dedicated todecoding video signals from a particular format, such as MPEG, foroutput and display on a television and for performing decryption. Itshould be understood that the functions performed by various modules ofFIG. 2 may be performed using one or more processors. As such, forexample, functions of descrambling engine 265 may be performed byprocessor 210.

Tuners 215 may include one or more tuners used to tune to televisionchannels, such as television channels transmitted via satellite orcable. Each tuner contained in tuners 215 may be capable of receivingand processing a single stream of data from a satellite transponder (ora cable RF channel) at a given time. As such, a single tuner may tune toa single transponder (or cable RF channel). If tuners 215 includemultiple tuners, one tuner may be used to tune to a television channelon a first transponder for display using a television, while anothertuner may be used to tune to a television channel on a secondtransponder for recording and viewing at some other time. Still anothertuner may be used to check various television channels to determine ifthey are available or not. If multiple television channels transmittedon the same transponder stream are desired, a single tuner of tuners 215may be used to receive the signal containing the multiple televisionchannels for presentation and/or recording.

Network interface 220 may be used to communicate via an alternatecommunication channel with a television service provider. For example,the primary communication channel may be via satellite (which may beunidirectional to the STB) and the alternate communication channel(which may be bidirectional) may be via a network, such as the Internet.Referring back to FIG. 1, STB 150 may be able to communicate withtelevision service provider system 110 via a network, such as theInternet. This communication may be bidirectional: data may betransmitted from STB 150 to television service provider system 110 andfrom television service provider system 110 to STB 150. Referring backto FIG. 2, network interface 220 may be configured to communicate viaone or more networks, such as the Internet, to communicate withtelevision service provider system 110 of FIG. 1. Information may betransmitted and/or received via network interface 220.

Storage medium 225 may represent a non-transitory computer readablestorage medium. Storage medium 225 may include memory and/or a harddrive. Storage medium 225 may be used to store information received fromone or more satellites and/or information received via network interface220. Storage medium 225 may store information related to EPG 230, NIT240, and/or DVR 245. Recorded television programs may be stored usingstorage medium 225.

EPG 230 may store information related to television channels and thetiming of programs appearing on such television channels. EPG 230 may bestored using non-transitory storage medium 225, which may be a harddrive. EPG 230 may be used to inform users of what television channelsor programs are popular and/or provide recommendations to the user. EPG230 may provide the user with a visual interface displayed by atelevision that allows a user to browse and select television channelsand/or television programs for viewing and/or recording via DVR 245.Information used to populate EPG 230 may be received via networkinterface 220 and/or via satellites, such as satellites 130 of FIG. 1via tuners 215. For instance, updates to EPG 230 may be receivedperiodically via satellite. EPG 230 may serve as an interface for a userto control DVR 245 to enable viewing and/or recording of multipletelevision channels simultaneously.

Audio/video decoder 233 may serve to convert encoded video and audiointo a format suitable for output to a display device. For instance,audio/video decoder 233 may receive MPEG video and audio from storagemedium 225 or descrambling engine 265 to be output to a television.Audio/video decoder 233 may convert the MPEG video and audio into aformat appropriate to be displayed by a television or other form ofdisplay device and audio into a format appropriate to be output fromspeakers, respectively.

Television interface 235 may serve to output a signal to a television(or another form of display device) in a proper format for display ofvideo and playback of audio. As such, television interface 235 mayoutput one or more television channels, stored television programmingfrom storage medium 225 (e.g., DVR 245 and/or information from EPG 230)to a television for presentation.

The network information table (NIT) 240 may store information used byset-top box 200 to access various television channels. NIT 240 may bestored using storage medium 225. Information used to populate NIT 240may be received via satellite (or cable) through tuners 215 and/or maybe received via network interface 220 from the television serviceprovider. As such, information present in NIT 240 may be periodicallyupdated. NIT 240 may be locally-stored by STB 200 using storage medium225. Information that may be present in NIT 240 may include: televisionchannel numbers, a satellite identifier, a frequency identifier, atransponder identifier, an ECM PID, one or more audio PIDs, and a videoPID. (A second audio PID of a channel may correspond to a second audioprogram (SAP), such as in another language). In some embodiments, NIT240 may be divided into additional tables. For example, rather than thespecific audio PIDs and video PIDs being present in NIT 240, a channelidentifier may be present within NIT 240 which may be used to lookup theaudio PIDs and video PIDs in another table.

Table 1 provides a simplified example of NIT 240 for several televisionchannels. It should be understood that in other embodiments, many moretelevision channels may be represented in NIT 240. NIT 240 may beperiodically updated by a television service provider. As such,television channels may be reassigned to different satellites and/ortransponders, and STB 200 may be able to handle this reassignment aslong as NIT 240 is updated.

TABLE 1 Channel Satellite Transponder ECM PID Audio PIDs Video PID 4 1 227 1001 1011 5 2 11 29 1002 1012 7 2 3 31 1003 1013 13 2 4 33 1003, 10041013

It should be understood that the values provided in Table 1 are forexample purposes only. Actual values, including how satellites andtransponders are identified, may vary. Additional information may alsobe stored in NIT 240. Additional information on how NIT 240, asindicated in Table 1, may be used is provided in reference to FIG. 3.Video and/or audio for different television channels on differenttransponders may have the same PIDs. Such television channels may bedifferentiated based on which satellite and/or transponder to which atuner is tuned.

Digital Video Recorder (DVR) 245 may permit a television channel to berecorded for a period of time. DVR 245 may store timers that are used byprocessors 210 to determine when a television channel should be tuned toand recorded to DVR 245 of storage medium 225. In some embodiments, alimited amount of storage medium 225 may be devoted to DVR 245. Timersmay be set by the television service provider and/or one or more usersof the STB. DVR 245 may be configured by a user to record particulartelevision programs. Whether a user directly tunes to a televisionchannel or DVR 245 tunes to a first television channel, NIT 240 may beused to determine the satellite, transponder, ECM PID (packetidentifier), audio PID, and video PID.

User interface 250 may include a remote control (physically separatefrom STB 200) and/or one or more button on STB 200 that allows a user tointeract with STB 200. User interface 250 may be used to select atelevision channel for viewing, view EPG 230, and/or program DVR 245.

Referring back to tuners 215, television channels received via satellite(or cable) may contain at least some encrypted data. Packets of audioand video may be scrambled to prevent unauthorized users (e.g.,nonsubscribers) from receiving television programming without paying thetelevision service provider. When a tuner of tuners 215 is receivingdata from a particular transponder of a satellite, the transponderstream may be a series of data packets corresponding to multipletelevision channels. Each data packet may contain a packet identifier(PID), which in combination with NIT 240, can be determined to beassociated with particular television channel. Particular data packets,referred to as entitlement control messages (ECMs) may be periodicallytransmitted. ECMs may be encrypted; STB 200 may use smart card 260 todecrypt ECMs. Decryption of an ECM may only be possible if the user hasauthorization to access the particular television channel associatedwith the ECM. When an ECM is received by demultiplexer 255 and the ECMis determined to correspond to a television channel being stored and/ordisplayed, the ECM may be provided to smart card 260 for decryption.

When smart card 260 receives an encrypted ECM from demultiplexer 255,smart card 260 may decrypt the ECM to obtain some number of controlwords. In some embodiments, from each ECM received by smart card 260,two control words are obtained. In some embodiments, when smart card 260receives an ECM, it compares the ECM to the previously received ECM. Ifthe two ECMs match, the second ECM is not decrypted because the samecontrol words would be obtained. In other embodiments, each ECM receivedby smart card 260 is decrypted; however, if a second ECM matches a firstECM, the outputted control words will match; thus, effectively, thesecond ECM does not affect the control words output by smart card 260.

When an ECM is received by smart card 260, it may take a period of timefor the ECM to be decrypted to obtain the control words. As such, aperiod of time, such as 2 seconds, may elapse before the control wordsindicated by the ECM can be obtained. Smart card 260 may be permanentlypart of STB 200 or maybe configured to be inserted and removed from STB200.

When an ECM is received by smart card 260, smart card 260 may not needto be informed which encryption scheme (e.g., a first or secondencryption scheme) was used to encrypt the ECM. The encryption schememay be determined by the number of bits present in the encrypted ECM.For instance, an encrypted ECM with a greater number of bits may beindicative of heavy encryption while an encrypted ECM with a fewernumber of bits may be indicative of light encryption. Regardless of thetype of encryption, upon receiving the encrypted ECM, the smartcard mayperform the processing necessary to output the control words from theECM. It may take a longer period of time for the smartcard to output theCWs determined from a heavy encrypted ECM than from a light encryptedECM. For an ECM encrypted using the heavy encryption scheme, decryptionmay take a longer period of time (and, thus, more processing) than anECM encrypted using a light encryption scheme. Regardless of whether CWsare obtained from a heavy encrypted ECM or a light encrypted ECM,descrambling of audio and/or video may be performed in a same mannerusing the CWs by descrambling engine 265.

It should be understood throughout that why embodiments detailed hereinrefer to heavy and light encryption, the encryption schemes used do notnecessary need have one encryption scheme stronger than the other. Forinstance, two encryption schemes may be different, without one beingstronger than the other (however, one may take less time to decrypt). Assuch, similar embodiments may be created that use a first encryptionscheme and a second encryption scheme. Further, more than encryptionschemes may be possible to be used, such as a light, medium, and heavyencryption scheme.

If greater than some number of television channels (e.g., 2) has itsassociated ECMs encrypted using heavy encryption, the smartcard may notbe able (due to programmed limits or processing limits of the smartcard)to decrypt the ECMs fast enough for both television channels to berecorded and/or presented simultaneously. Synchronization may becoordinated by the television service provider. Accordingly, thesmartcard may receive combinations of heavy encrypted ECMs and lightencrypted ECMs that the smartcard is known to be able to decodesufficiently timely to permit simultaneous recording and/or presentationof the associated television channels.

Demultiplexer 255 may be configured to filter data packets based onPIDs. For example, if a transponder data stream includes multipletelevision channels, data packets corresponding to a television channelthat is not desired to be stored or displayed by the user, may beignored by demultiplexer 255. As such, only data packets correspondingto the one or more television channels desired to be stored and/ordisplayed may be passed to either descrambling engine 265 or smart card260, other data packets may be ignored. For each channel, a stream ofvideo packets, a stream of audio packets and/or a stream of ECM packetsmay be present, each stream identified by a PID. In some embodiments, acommon ECM stream may be used for multiple television channels.Additional data packets corresponding to other information, such asupdates to NIT 240, may be appropriately routed by demultiplexer 255.

Descrambling engine 265 may use the control words output by smart card260 in order to descramble video and/or audio corresponding totelevision channels for storage and/or presentation. Video and/or audiodata contained in the transponder data stream received by tuners 215 maybe scrambled. The video and/or audio may be descrambled by descramblingengine 265 using a particular control word. Which control word output bysmart card 260 to be used for successful descrambling may be indicatedby a scramble control identifier present within the data packetcontaining the scrambled video or audio. Descrambled video and/or audiomay be output by descrambling engine 265 to storage medium 225 forstorage (via DVR 245) and/or to audio/video decoder 233 for output to atelevision or other presentation equipment via television interface 235.

For simplicity, STB 200 of FIG. 2 has been reduced to a block diagram,commonly known parts, such as a power supply, have been omitted.Further, some routing between the various modules of STB 200 has beenillustrated. Such illustrations are for exemplary purposes only. Twomodules not being directly or indirectly connected does not indicate themodules cannot communicate. Rather, connections between modules of theSTB 200 are intended only to indicate possible common data routing. Itshould be understood that the modules of STB 200 may be combined into afewer number of modules or divided into a greater number of modules.Further, the components of STB 200 may be part of another device, suchas built into a television. Also, while STB 200 may be used to receive,store, and present television channels received via a satellite, itshould be understood that similar components may be used to receive,store, and present television channels via a cable network.

FIG. 3 illustrates an embodiment of a television service providerscrambling system 300. Television service provider scrambling system 300may be part of television service provider system 110 of FIG. 1. Assuch, before data is transmitted to set-top boxes via satellite,television service provider scrambling system 300 may be used toscramble video and/or audio packets to prevent unauthorized users fromaccessing television programming. Television service provider scramblingsystem 300 may include: television programming module 310, control wordgenerator 320, security system 330, multiplexer 340, scrambling engine350, transmitter 360, and encryption synchronizer 370.

Television programming module 310 may receive television channels frommultiple different sources, such as directly from the networks thatproduced the content on the television channels. Each television channelthat is to be transmitted on a particular transponder stream via atransponder of the satellite may be provided to multiplexer 340.Multiplexer 340 may create a digital stream of data packets containingthe video, audio, and other data, such as ECMs, to be transmitted on thetransponder data stream. The data stream, which includes video and/oraudio data packets that are not scrambled, may be passed to scramblingengine 350. Scrambling engine 350 may use a control word to scramblevideo or audio present in a data packet. Some audio and video packetsmay also pass through with no scrambling, if desired by the televisionservice provider.

Control word generator 320 may generate the control word that is used byscrambling engine 350 to scramble the video or audio present in the datapacket. Control words generated by control word generator 320 may bepassed to security system 330, which may be operated by the televisionservice provider or by a third-party security provider.

The control words generated by control word generator 320 may be used bysecurity system 330 to generate an ECM. Each ECM may indicate twocontrol words. The control words indicated may be the current controlword being used to scramble video and audio, and the control word thatwill next be used to scramble video and audio. Whether an ECM is createdfor the two controls words using heavy or light encryption may bedetermined by encryption synchronizer 370.

Encryption synchronizer 370 may determine which television channels areto be encrypted using heavy or light encryption and may control how theheavy and light encryption is cycled through the channels. For instance,encryption synchronizer 370 may receive data from multiplexer 340 (orsome other source, such as an administrator of the television serviceprovider) that indicates which television channels are transmitted usingthe same transponder stream. In some embodiments, heavy encryption isrotated among television channels transmitted as part of the sametransponder stream. Encryption synchronizer 370 may provide securitysystem 330 with an indication of which television channels should beassociated with a heavy encrypted ECM and which television channelsshould be associated with a light encrypted ECM. The designation maychange periodically, such as every ten seconds.

As an example, if television channels 1, 2, 3, 4, and 5 are groupedtogether for transmission using a single transponder stream, multiplexer340 may provide an indication of this group of television channels toencryption synchronizer 370, which may be operated by the televisionservice provider or a third-party entity which may be operating securitysystem 330. Based on the group of television channels and having anindication of the number of heavy encrypted ECMs (e.g., one) that asmartcard of a STB can handle over a given period, encryptionsynchronizer 370 may provide an indication to security system 330 of howECMs should be encrypted, such as exemplified in Table 2.

TABLE 2 Time (in Television Television Television Television Televisionseconds) Channel 1 Channel 2 Channel 3 Channel 4 Channel 5  0 s-10 sHeavy Light Light Light Light 10 s-20 s Light Heavy Light Light Light 20s-30 s Light Light Heavy Light Light

Since the processing capabilities of a television service provider'sSTBs' smartcards may be known, encryption synchronizer 370 may beconfigured such that a smartcard does not receive more heavy encryptedECMs than the smartcard can handle for a given time period (such thatwhen a particular CW is needed for descrambling by the STB, the CW hasbeen decrypted from the ECM by the smartcard and is available for use).

Security system 330 may create and output an ECM to multiplexer 340 fortransmission to subscribers' set-top boxes based on the encryptionscheme indicated by encryption synchronizer 370 and the CWs indicated bycontrol word generator 320. Each data packet, whether it contains audio,video, an ECM, or some other form of data, may be associated with a PID.PIDs may be used by the set-top box in combination with the networkinginformation table to determine which television channel the datacontained within the data packet corresponds. After video and audiocontained within data packets has been scrambled by scrambling using aCW engine 350, the transponder data stream may be transmitted bytransmitter 360 to a satellite, such as satellite 130-1 of FIG. 1, forrelay to subscribers' set-top boxes, such as STB 150. Accordingly, thetransponder data stream transmitted by transmitter 360 containsscrambled video packet stream and audio packet stream and also containsan encrypted ECM packet stream which, when decrypted, provides thecontrol words necessary to descramble the scrambled video and audiopackets.

For simplicity, television service provider scrambling system 300 ofFIG. 3 has been reduced to a block diagram, other common components havebeen omitted. Further, some routing between the various modules oftelevision service provider scrambling system 300 has been illustrated.Such illustration is for exemplary purposes only. Regardless of whethertwo modules are directly or indirectly connected, the modules may beable to communicate. Connections between modules are intended only toindicate possible common routing. It should be understood that themodules of television service provider scrambling system 300 may becombined into a fewer number of modules or divided into a greater numberof modules.

FIG. 4 illustrates an embodiment of a data transmission and encryptionscheme for satellite television channel distribution. In FIG. 4, atransponder data stream 400 is illustrated. At least some data containedwithin data packets of transponder data stream 400 are scrambled usingcontrol words. In some embodiments, at least audio and video datacontained within data packets are scrambled using control words.Referring to transponder data stream 400, video and audio packetstransmitted during a first time period 410-1 are scrambled using a firstcontrol word. Video and audio transmitted during a second time period410-2 is scrambled using a second control word. Video and audiotransmitted during a third time period 410-3 is scrambled using a thirdcontrol word, and so on. In order to descramble video and audio receivedduring a particular time period, the appropriate control word must beused for descrambling.

Data packet 420 illustrates an exemplary video or audio packet. Datapacket 420 may contain at least: PID 430, sync 440, scramble control450, and payload 460. The packet header of the packet (which may be anMPEG packet) may include PID 430, sync 440, and scramble control 450.PID 430 may be a packet identifier used to indicate the particulartelevision channel (or other type of data, such as an ECM) with whichthe data packet is associated. Multiple video packets associated withthe same PID may be referred to as a video packet stream, likewise forECMs and audio packets. Referring back to Table 1, if a particulartelevision channel is attempting to be accessed, such as televisionchannel four, using the NIT, the STB may be able to determine that adata packet with a PID of 1001 corresponds to audio for channel 4, adata packet with a PID of 1011 corresponds to video for channel 4, and adata packet with a PID of 27 corresponds to an ECM for channel 4. Sync440 may contain some number of bits that are used to synchronize withthe transport stream. Scramble control 450 may serve to indicate whichcontrol word, if any, should be used to descramble payload 440. In someembodiments, scramble control 450 may indicate either an even controlword or an odd control word is to be used for decryption. In a video oraudio packet, payload 460 may contain scrambled video or audio,respectively.

When a data packet is received that indicates a PID corresponding to anECM of a television channel desired to be recorded or viewed, theencrypted ECM in the payload may be passed to a smart card fordecryption. As the control word used for descrambling is changed overtime, so is the ECM. Each ECM may contain the currently used controlword for descrambling and the control word that will be used fordescrambling next. As such, an ECM may contain one control word that isthe same as the previous ECM and a new control word. For example, an ECMmay be represented in the format of (CW_(odd), CW_(even)). Whether theeven or the odd control word is used for descrambling may be based onthe scramble control identifier present within a data packet.

During the time period 410-1 the odd control word, CW₁, may be used fordescrambling. During this time period, the same ECM may be receivedmultiple times (which may allow a set-top box that just tuned to thetransponder stream to access television channels using the ECM's CWs assoon the ECMs are decrypted and the CW recovered). This ECM may includeencrypted (CW₁, CW₂). As such, the ECM indicates the current controlword (CW₁) and the next control word to be used (CW₂). During timeperiod 410-1 data packets containing scrambled data may have scramblecontrol bits that indicate the odd control word should be used fordescrambling, as such CW₁ may be used for descrambling.

Starting at the beginning of time period 410-2, the scramble controlbits of a data packet containing scrambled video or audio may indicatethe even control word should be used, as such CW₂ may be used fordescrambling. Once time period 410-2 begins, and control word CW₁ is nolonger being used for descrambling, a different ECM may be transmittedto the STB that indicates the current control word and the next controlword to be used. This ECM may be transmitted periodically during timeperiod 410-2, such as every tenth of a second. In this instance, the ECMmay indicate: (CW₃, CW₂). As such, the current control word CW₂ remainsthe same and continues to be used for descrambling during time period410-2 during which the data packets indicate, via their scramble controlbits, that the even control word is to be used for descrambling. Whendecrypted, the new ECM indicates a new odd control word, CW₃, which willbe used for descrambling when the scramble control bits indicate the oddcontrol word should be used for descrambling. This process may continue,with descrambling switching between the even and odd control words aslong as the STB is tuned to the transponder stream. In some embodiments,the time period during which any particular control word is used may beapproximately 10 seconds. Such a time period may allow ample time for asmartcard to decrypt an ECM such that the next control word to be usedwill be decrypted by the smart card prior to data packets being receivedthat indicate, via the scramble control bits, that this next controlword is to be used for descrambling.

Transponder data stream 400 may contain audio and video for multipletelevision channels, the packets of which may be indicated by differentPIDs. In FIG. 4, a single CW is shown as used for discrete time periods,however it should be understood that different CWs may be decrypted fromdifferent ECMs for different television channels. As such, theillustration of CWs one through five may be for one (or more than one)television channel, while other CWs (decrypted from other ECMs) may beused for other television channels within the transponder stream.

While data packet 420 indicates only PID 430, sync 440, scramble control450, and payload 460 as parameters that are present, it should beunderstood that data may be present that corresponds to otherparameters, such as other header parameters. Further, based on theembodiment, the number of bits or bytes present in scramble control 450,payload 460, PID 430, sync 440 and/or any other parameter may vary. Theboxes present in data packet 420 are not intended to be representativeof a particular number of bits or bytes.

FIG. 5 illustrates an embodiment of multiple encryption schemes of ECMs500 corresponding to multiple television channels. While transponderstream 400 of FIG. 4 represents all of the data packets received via atransponder stream, FIG. 5 illustrates audio and video packets sortedaccording to television channel. As such, each of television channelsone through four may have been received as part of the same transponderstream or in a different transponder streams. Television channels onethrough four may have been received as part of transponder stream 400.The multiple encryption schemes of ECMs 500 may be determined bysecurity system 330, control word generator 320, and encryptionsynchronizer 370 of the television service provider that scrambles thetelevision channels and encrypts the ECMs prior to transmitting each tousers' set top boxes.

In FIG. 5, The multiple encryption schemes of ECMs 500 are illustratedin the time domain. Audio/video data packet group 510 may be received bya set top box between 0 seconds and 10 seconds. During this same timeperiod, audio/video data packet groups 515, 520, and 525 may also bereceived by the set top box. If received as part of the same transponderstream, each of these packets may be received at slightly differenttimes within the time period between 0 and 10 seconds. To decode some orall of these groups of audio/video data packets, ECMs received by a settop box may need to be decrypted to obtain the control words necessaryto descramble the audio/video packets associated with each televisionchannel. Received within audio/video data packet group 510 (or at someearlier time) may be one or more ECMs corresponding to televisionchannel one. Received among audio/video data packet group 515 (or atsome earlier time) may be one or more ECMs corresponding to televisionchannel two. Received among audio/video data packets 520 (or at someearlier time) may be one or more ECMs corresponding to televisionchannel three. Received among audio/video data packets 520 (or at someearlier time) may be one or more ECMs corresponding to televisionchannel four. In order for a particular television channel to bepresented (such as via a television) and/or recorded (such as via aDVR), the television channel's audio/video data packets may need to bedescrambled using a control word obtained from an ECM corresponding tothe television channel.

Each ECM received by the STB may be encrypted. While each ECM may beencrypted, the encryption scheme for one or more of the ECMs may vary.In FIG. 5, audio/video data packet groups required to be descrambledusing a control word obtained from a heavy encrypted ECM are bolded.Therefore, audio/video data packet group 510 requires a control wordobtained from a heavy encrypted ECM for descrambling. The remainingtelevision channels during the same time period may use a differentencryption scheme. Audio/video data packet groups 515, 520, and 525 eachuse light encryption during this time period of 0 to 10 seconds.Therefore, during the time period of 0 seconds to 10 seconds, onlytelevision channel one has video/audio data packets requiring a controlword for descrambling from a heavy encrypted ECM; television channelstwo, three, and four have audio/video data packets requiring controlwords from light encrypted ECMs. Therefore, in order to obtain thecontrol words necessary to descramble channels one through four over thetime period of 0 seconds to 10 seconds, a smartcard of a set top box mayonly need to decrypt a single heavy encrypted ECM and three lightencrypted ECMs.

During the time period of 10 seconds to 20 seconds, which televisionchannel requires a control word from a heavy encrypted ECM has rotated.Audio/video data packet groups 530, 540, and 545 each are descrambledusing control words obtained from light encrypted ECMs. Audio/video datapackets from audio/video data packet group 535 are descrambled using acontrol word decrypted from a heavy encrypted ECM. Accordingly, for thetime period of 10 seconds to 20 seconds, a smartcard of a set top box isagain only required to decrypt a single heavy encrypted ECM and threelight encrypted ECMs, albeit during this time period the televisionchannel descrambled using a control word decrypted from a heavyencrypted ECM has changed. This pattern may continue for additionalaudio/video data packet groups later in time such that audio/video datapacket groups for television channel three and television channel fourare also associated with an ECM encrypted using heavy encryption. In theillustrated embodiment, at 40 seconds, after each of the televisionchannels have been associated with an ECM encrypted using heavyencryption, audio/video data packets associated with channel one mayagain need to be descrambled using a control word obtained from a heavyencrypted ECM. As such, audio/video data packet group 550 may require acontrol word be obtained from a heavy encrypted ECM, while audio/videodata packet groups 555, 560, and 565 require control words from lightencrypted ECMs for descrambling. Regardless of whether control words areobtained from a heavy or light encrypted ECM, the descrambling processusing the CWs may remain the same across the television channels.

Each of television channels one through four may be transmitted using asingle transponder stream. As such, if a set top box has been configuredto present and/or store some or all of the television channelstransmitted using a particular transponder stream, encryption of theECMs for each television channel can be synchronized such that the STB'ssmartcard has only a limited number of heavy encrypted ECMs to decryptfor a given time period (such as one every ten seconds). As such, it canbe ensured that a smartcard receives ECMs than can be decrypted toobtain the CWs in time for descrambling of the associated televisionchannels.

In the illustrated embodiment of FIG. 5, four television channels arepresented with a heavy encrypted ECM being associated with eachtelevision channel in sequence; this arrangement is for example purposesonly. The number of television channels through which heavy/lightencryption cycling may occur can vary. For instance, the heavy/lightencryption may cycle through each television channel in a particulartransponder stream. Further, the cycling may not need to be in asequential manner, which is illustrated. Also, the time period afterwhich cycling occurs may vary by embodiment (e.g., cycle every 30seconds instead of every 10 seconds). The number of television channelsthat can be concurrently associated with heavy encryption may vary. Forinstance, this may be based on the capabilities of a smartcard in theset top boxes. In some embodiments, one, two, three, or more televisionchannels may be associated with a heavy encrypted ECM and may bedecrypted by a smartcard in a sufficiently timely manner to permit thecontrol words to be obtained for descrambling of audio and video datapackets.

FIG. 6 illustrates another embodiment of multiple encryption schemes ofECMs 600 corresponding to multiple television channels. Whiletransponder stream 400 of FIG. 4 represents all of the data packetsreceived via a transponder stream, FIG. 6, like FIG. 5, illustratesaudio and video packets sorted (for visualization purposes) according totelevision channel. As such, each of television channels one throughfour in FIG. 6 may have been received as part of the same transponderstream or in a different transponder streams. Television channels onethrough four may have been received as part of transponder stream 400.The multiple encryption schemes of ECMs 600 may be designated bysecurity system 330, control word generator 320, and encryptionsynchronizer 370 of the television service provider that scrambles thetelevision channels and encrypts the ECMs prior to transmitting each tousers' set top boxes. The multiple encryption schemes of ECMs 600 mayrepresent an alternate embodiment to multiple encryption schemes of ECMs500 of FIG. 5.

In multiple encryption schemes of ECMs 500 of FIG. 5, out of a group offour television channels, heavy and light encryption was cycled for eachtelevision channel individually. In some embodiments, the same ECM,whether encrypted using heavy or light encryption, may be used to obtainCWs for descrambling of more than one television channel. For example,referring to Table 1, it may be possible to assign multiple televisionchannels the same ECM PID (for example, television channels 4 and 5could each be assigned an ECM PID of 27). Therefore, ECMs with the samePIDs would be used to obtain the CWs for each television channel. In themultiple encryption schemes of ECMs 600, two television channels areassigned to each ECM. Television channel one and two correspond to afirst ECM PID and television channels three and four correspond to asecond ECM PID. Therefore, rather than four ECMs needing to be decryptedfor each time period (in this example, 10 seconds), only two ECMs needto be decrypted for each time period.

In FIG. 6, The multiple encryption schemes of ECMs 600 are illustratedin the time domain. Audio/video data packet group 610 may be received bya set top box between 0 seconds and 10 seconds. During this same timeperiod, audio/video data packet groups 615, 620, and 625 may also bereceived by the set top box. The audio and video packets for eachtelevision channel may be distinguished by different PIDs, such aspresented in Table 1. However, the control words used to scramble eachtelevision channel may match between channels one and two and betweenchannels three and four such that one ECM may be decrypted to obtain thecontrol word for channels one and two, and one ECM may be decrypted toobtain the control word for channels three and four. Each data packetmay be received at slightly different times within the time periodbetween 0 and 10 seconds. Interspersed within the transponder stream maybe one or more ECMs corresponding to television channels one and two.Interspersed within the transponder stream may be one or more ECMscorresponding to television channels three and four. Based on PIDs inthe NIT (or some other locally-stored table), the STB may determine thatan ECM stream associated with a particular PID is associated withmultiple television channels. In order for a particular televisionchannel to be presented (such as via a television) and/or recorded (suchas via a DVR), the television channel's audio/video data packets mayneed to be descrambled using a control word obtained from an ECMcorresponding to the television channel.

As in FIG. 5, audio/video data packets associated with CWs obtained froma heavy encrypted ECM are bolded. As such, audio/video data packetgroups 610 and 615 require a control word for descrambling from a heavyencrypted ECM; audio/video data packet groups 620 and 625 require acontrol word for descrambling from a light encrypted ECM. Since multipletelevision channels share ECMs, for the time period of 0-10 s, only twoECMs may need to be decrypted. Other embodiments may use variations onthe theme of using a same ECM for multiple television channels. Forinstance, television channels one, two, and three may use the same ECMstream, while television channel four uses a different ECM stream.

For the time period of 10 s-20 s, the encryption scheme may rotate suchthat the ECM used to obtain the control words for audio/video datapacket groups 640 and 645 is heavy encrypted, while the ECM used toobtain the control words for audio/video data packet groups 630 and 635is light encrypted. For time period of 20 s-30 s, the encryption mayrotate back to the same arrangement as the first time period. As such,the ECM used to obtain the control words for audio/video data packetgroups 650 and 655 are heavy encrypted, while the ECM used to obtain thecontrol words for audio/video data packet groups 660 and 665 are lightencrypted. In such an embodiment, each television channel is protectedby a heavy encrypted ECM for 50% of the time. However, the smartcard ofthe STB may have to perform less overall processing because only twoECMs are needed for the four television channels. In some embodiments,because fewer ECMs need to be decrypted, a heavier level of encryptionmay be used for each ECM (which may take the smartcard of a STB longerto decrypt). Such an arrangement may be preferable because it may bemore difficult for a non-subscriber to crack a heavier encrypted ECMused for multiple television channels rather than a lighter encryptedECM used for a fewer (e.g., one) television channels.

From the embodiments of FIGS. 5 and 6, it may be possible to determineother encryption schemes that can be used over multiple televisionchannels which may be transmitted as part of the same transponderstream. While the above description focuses on heavy and lightencryption, such embodiments may be applied more generally to a firstand second encryption scheme. As such, rather than one encryption schemebeing more difficult to decrypt, different encryption methods may bepresent for each encryption scheme. The number of television channelsand the length of the time periods used are for example purposes only.Further, in some embodiments, more than two encryption schemes may beused to encrypt ECMs.

The various encryption schemes and systems described herein may be usedto perform various methods. FIG. 7 illustrates an embodiment of a method700 for using multiple encryption schemes for encryption of entitlementcontrol messages (ECMs) within a transponder stream. Method 700 may beperformed by a television service provider system for transmittingtelevision channels to STBs via satellite, such as presented in system100 of FIG. 1. Method 700 may also be applied to a cable televisiondistribution system. At least some steps of method 700 may be performedusing a computer system. Television service provider system 300 of FIG.3 may be used to perform at least some of the steps of method 700. Assuch, means for performing method 700 can include one or more computersand/or any of the components of systems 100, 200, and/or 300.

At step 710, a group of television channels may be selected to transmitto multiple STBs using a single transponder stream. By using a singletransponder stream, it may be possible to use a single tuner at a settop box to receive each of the television channels. In a satellite-basedtelevision distribution system, groups of television channels may betransmitted to user equipment via multiple transponders which may belocated on one or more satellites. The television channels may begrouped into particular transponder streams based on television channelsthat a subscriber may be likely to want to watch and/or record at thesame time. As such, the amount of hardware necessary at the set top boxmay be minimized by having such television channels transmitted in thesame transponder stream.

At step 720, within the group of television channels selected at step710, a first television channel may be designated to be protected via afirst ECM that is encrypted using a first encryption scheme. Forexample, this first encryption scheme may be heavy encryption whichtakes longer to decrypt by a set top box than an ECM encrypted usinglight encryption. At step 730, within the group of television channelsselected it step 710, a second television channel may be designated tobe protected via a second ECM that is encrypted using a secondencryption scheme. As an example, if the group of television channelsselected at step 710 includes 6 television channels, one of thetelevision channels may be selected to be protected using an ECMencrypted using a first encryption scheme while the other fivetelevision channels are protected using ECMs that are encrypted using asecond encryption scheme. This second encryption scheme may be a lightencryption scheme which takes less time and/or less processing todecrypt that an ECM encrypted using heavy encryption. As a simpleexample, the heavy encryption may be 128-bit encryption while the lightencryption may be 64-bit encryption. The designations of steps 720 and730 may be for predefined period of time after which encryption mayrotate such that the television channels are protected using otherencryption schemes.

At step 740, the first encrypted ECM and the second encrypted ECM may becreated. The first encrypted ECM may be created in accordance with thefirst encryption scheme and the second encrypted ECM may be created inaccordance with the second encryption scheme. Each encrypted ECM may becreated to contain control words that are provided to the componentcreating the ECMs. An indication may also be provided to the componentcreating the ECMs as to which encryption scheme should be used toencrypt the ECM. In some embodiments, each ECM contains two controlwords. Referring to FIG. 3, security system 330 may be used to createthe ECMs. Security system 330 may be operated by the television serviceprovider or by a third-party provider. The television service provideror the third-party provider may operate a control word generator thatcreates the control words which are used to scramble the televisionchannels. These control words along with input from encryptionsynchronizer, which may specify the encryption scheme to be used toencrypt the control words may be used by the security system to createthe ECMs encrypted using the first and second encryption schemes.

At step 750, the first encrypted ECM and a second encrypted ECM may betransmitted to the multiple set top boxes. Referring to FIG. 1, asatellite television distribution system may be used to transmit thefirst and second ECMs to multiple set top boxes. The first and secondencrypted ECMs may be transmitted to set top boxes in a transponderstream containing data packets associated with audio and video fortelevision channels. Such a transponder stream may also include dataused to update a table stored at the set top box and/or provide otherservices to subscribers.

At step 760, audio and video packets corresponding to the firsttelevision channel and the second television channel may be transmittedto the set top boxes possibly using the single transponder stream. Overa given time period, such as a period of 10 seconds, audio and videodata packets corresponding to each television channel may be transmittedas part of the transponder stream. Over this time period, the set topbox may have the ability to record and/or present either televisionchannel. As such, the first television channel and second televisionchannel are considered to be concurrently transmitted and concurrentlyreceived. For example, over the same time period, such as from 8 PM to8:30 PM, either television channel may be tuned to for differenttelevision programs. The first television channel may be scrambled usingone or more control words encrypted in the first ECM. The secondtelevision channel may be scrambled using one or more control wordsencrypted in the second ECM. Accordingly, in order to descramble thefirst and second television channels, the ECM encrypted using the firstencryption scheme and the second ECM encrypted using the secondencryption scheme may need to be decrypted by a set top box. Suchdecryption may be performed by the smart card at the set top box. Byusing two different encryption schemes, the amount of processingnecessary to be performed at the set top box may be decreased. Such adecrease in processing may permit control words to be obtained from theECMs in time to permit descrambling of the corresponding televisionchannels when the control words have started being used to scramble thetelevision channels.

At step 770, the encryption schemes may be rotated. Rotating theencryption schemes may involve ECMs that were previously encrypted usingthe first encryption scheme now being encrypted using the secondencryption scheme. Similarly, ECMs that were previously encrypted usingthe second encryption scheme may now be encrypted using the firstencryption scheme. Therefore, when method 700 repeats, at step 720, thesecond encryption scheme may be used and at step 730 the firstencryption scheme may be used. Such rotation may allow each televisionchannel at different periods of time to be encrypted using eachencryption scheme. It may not be necessary for the television serviceprovider to provide any indication of which encryption scheme is usedfor which ECM to a STB. Based on the properties of the ECM, a smartcardof a set top box may be able to determine the processing necessary todecrypt the ECM.

FIG. 8 illustrates an embodiment of a method for receiving multipletelevision channels corresponding to ECMs encrypted using multipleencryption schemes within a single transponder stream. Method 800 may beperformed by a set top box that receives television channels via asatellite dish and satellite, such as presented in system 100 of FIG. 1.Method 800 may also be applied to a cable television distributionsystem, such as via a STB that receives RF cable television service. Atleast some steps of method 800 may be performed using a computer system.STB 200 of FIG. 2 may be used to perform at least some of the steps ofmethod 800. As such, means for performing method 800 can include one ormore computers and/or any of the components of systems 100, 200, and/or300. Method 800 may be performed by a set top box following method 700being performed by a television service provider.

At step 810, a first ECM encrypted using a first encryption scheme maybe received by a set top box. The first encrypted ECM may contain anunencrypted PID. Based on this period, the set top box may determinewhether the first encrypted ECM is associated with a television channelthat is being presented and/or stored. If the television channel is notbeing presented or stored, the first encrypted ECM may be ignored.However, if the first encrypted ECM is associated with a televisionchannel that is being output for presentation (e.g., via a television)and/or stored by the set top box, the first encrypted ECM may be routedwithin the set top box for decryption. The first encrypted ECM may berouted to a smartcard within the set top box for decryption. For theexample of method 800, it is assumed that the first encrypted ECM isassociated with a television channel that is being output forpresentation and/or recorded by the set top box. The first encrypted ECMmay be received as part of a transponder stream that contains multipletelevision channels that were grouped together into a single transponderstream by the television service provider.

At step 820, the first encrypted ECM may be decrypted by the set topbox. The decryption may be performed by a smartcard at the set top box.As such, the first encrypted ECM may be routed within the set top box tothe smartcard for decryption. When the first encrypted ECM is receivedby the smart card, the smartcard may process the first encrypted ECMuntil it is decrypted. Once successfully decrypted, two control wordsmay be obtained from the first encrypted ECM. The smartcard may be ableto determine the proper way to decrypt the first encrypted ECMregardless of whether the ECM is encrypted using the first or secondencryption scheme. For instance, based on the number of bits received,the smartcard may be able to determine the proper way to decrypt thefirst encrypted ECM. The smartcard may continue processing the firstencrypted ECM until it has been successfully decrypted. The amount oftime the smartcard requires to successfully decrypt the first encryptedECM may be based on the encryption scheme used for encryption of thefirst ECM.

At step 830, a second ECM encrypted using a second encryption scheme maybe received by the set top box. This second encrypted ECM may beassociated with one or more television channels other than the one ormore television channels associated with the first encrypted ECM. Thefirst encrypted ECM and the second encrypted ECM may be received as partof the same transponder stream. The first encrypted ECM and the secondencrypted ECM may correspond to different television channelstransmitted and received via the same transponder stream.

The second encrypted ECM may contain an unencrypted PID. Based on thisPID, the set top box may determine whether the second encrypted ECM isassociated with a television channel that is being presented and/orstored. If the television channel is not being presented or stored, thesecond encrypted ECM may be ignored. However, if the second encryptedECM is associated with the television channel that is being output forpresentation (e.g., via a television) and/or stored by the set top box,the second encrypted ECM may be routed within the set top box fordecryption. The second encrypted ECM may be routed to the smartcardwithin the set top box for decryption. For the example of method 800, itis assumed that, like the first encrypted ECM, the second encrypted ECMis associated with one or more television channels that are being outputfor presentation and/or recorded by the set top box. The secondencrypted ECM may be received as part of the transponder stream thatcontains multiple television channels that were grouped together into asingle transponder stream by the television service provider, includingthe first television channel.

At step 840, the second encrypted ECM may be decrypted by the set topbox. The decryption may be performed by the smartcard at the set topbox. As such, the second encrypted ECM may be routed within the set topbox to the smartcard for decryption. When the second encrypted ECM isreceived by the smart card, the smartcard may process the secondencrypted ECM until it is decrypted. Once successfully decrypted, twocontrol words may be obtained from the second encrypted ECM for use indescrambling a second television channel. The smartcard may be able todetermine the proper way to decrypt the second encrypted ECM regardlessof whether the ECM is encrypted using the first or second encryptionscheme. The smartcard may process the second encrypted ECM until it hasbeen successfully decrypted. The amount of time the smartcard requiresto successfully decrypt the second encrypted ECM may be based on theencryption scheme used for encryption of the second ECM. For example, ifthe second encryption scheme is a light encryption scheme while thefirst encryption scheme is a heavy encryption scheme, the secondencrypted ECM may take less time for the smartcard to decrypt than thefirst encrypted ECM.

At step 850, audio and video packets corresponding to the firsttelevision channel and the second television channel may be received.Based on a locally stored network information table that identifies theassociated ECM PID and the scramble control bits of the audio and videopackets, the proper control words decrypted from the first encrypted ECMand the second encrypted ECM may be determined for use in descramblingthe audio and video data packets. For the first television channel and asecond television channel to be properly output for presentation and/orrecorded by the set top box, it may be necessary for the appropriatecontrol words to have been decrypted from the ECMs for use indescrambling. As such, when the television channel is being presented orrecorded, the smartcard may be required to successfully decrypt theassociated ECM to obtain the necessary control word for descramblingprior to the STB processing audio and/or video packets scrambled usingthat control word. To ensure that the smartcard decrypts all necessaryECMs prior to the control words contained in the ECMs being needed, theencryption schemes used for encryption of the ECMs may be synchronizedby the television service provider such that the smartcard will havesufficient time to decrypt each necessary ECM. This may occur on atransponder stream by transponder stream basis, meaning, it may beassured that a smartcard can decrypt the ECMs for all televisionchannels in a particular transponder stream in a timely manner.

At step 860, the control words from the first ECM and the second ECM maybe used to descramble the first television channel and the secondtelevision channel concurrently. As such, television programs broadcastsimultaneously on the two television channels may both be output forpresentation and/or recorded by the set top box. Once the control wordshave been obtained from the first ECM and the second ECM, regardless ofthe encryption scheme used for each ECM, the scrambling may be performedusing the control words obtained in the same manner. At step 870, thedescrambled first television channel and the descrambled secondtelevision channel may be output for presentation and/or stored by theset top box. Following step 870, after a period of time, such as 10seconds, new ECMs may need to be decrypted to obtain new control wordsfor descrambling of the television channels. As such, method 800 mayrepeat the encryption scheme for each ECM may change.

It should be understood that while method 800 is directed to twotelevision channels and encryption schemes, other embodiments of method800 may involve more than two encryption schemes and/or more than twotelevision channels. Further, a single ECM, based on its PID, may beassociated with more than one television channel. For example, referringto FIG. 6, multiple channels can be associated with a common ECM. Insome embodiments, ECMs associated with different television channels maybe encrypted using the same encryption scheme. For instance, referringto FIG. 5, at a given time, one television channel may be associatedwith an ECM encrypted using a first encryption scheme while three othertelevision channels in the same transponder stream may be associatedwith ECMs encrypted using a second encryption scheme.

FIG. 9 illustrates an embodiment of a computer system. A computer systemas illustrated in FIG. 9 may be incorporated as part of the previouslydescribed computerized devices, such as the television service providersystem and the set top boxes. Set top boxes may be combined with othersystems, such as being subsystem of a television. FIG. 9 provides aschematic illustration of one embodiment of a computer system 900 thatcan perform the methods provided by various other embodiments, asdescribed herein. It should be noted that FIG. 9 is meant only toprovide a generalized illustration of various components, any or all ofwhich may be utilized as appropriate. FIG. 9, therefore, broadlyillustrates how individual system elements may be implemented in arelatively separated or relatively more integrated manner.

The computer system 900 is shown comprising hardware elements that canbe electrically coupled via a bus 905 (or may otherwise be incommunication, as appropriate). The hardware elements may include one ormore processors 910, including without limitation one or moregeneral-purpose processors and/or one or more special-purpose processors(such as digital signal processing chips, graphics accelerationprocessors, and/or the like); one or more input devices 915, which caninclude without limitation a mouse, a keyboard, and/or the like; and oneor more output devices 920, which can include without limitation adisplay device, a printer, and/or the like.

The computer system 900 may further include (and/or be in communicationwith) one or more non-transitory storage devices 925, which cancomprise, without limitation, local and/or network accessible storage,and/or can include, without limitation, a disk drive, a drive array, anoptical storage device, a solid-state storage device, such as a randomaccess memory (“RAM”), and/or a read-only memory (“ROM”), which can beprogrammable, flash-updateable and/or the like. Such storage devices maybe configured to implement any appropriate data stores, includingwithout limitation, various file systems, database structures, and/orthe like.

The computer system 900 might also include a communications subsystem930, which can include without limitation a modem, a network card(wireless or wired), an infrared communication device, a wirelesscommunication device, and/or a chipset (such as a Bluetooth™ device, an802.11 device, a WiFi device, a WiMax device, cellular communicationfacilities, etc.), and/or the like. The communications subsystem 930 maypermit data to be exchanged with a network (such as the networkdescribed below, to name one example), other computer systems, and/orany other devices described herein. In many embodiments, the computersystem 900 will further comprise a working memory 935, which can includea RAM or ROM device, as described above.

The computer system 900 also can comprise software elements, shown asbeing currently located within the working memory 935, including anoperating system 940, device drivers, executable libraries, and/or othercode, such as one or more application programs 945, which may comprisecomputer programs provided by various embodiments, and/or may bedesigned to implement methods, and/or configure systems, provided byother embodiments, as described herein. Merely by way of example, one ormore procedures described with respect to the method(s) discussed abovemight be implemented as code and/or instructions executable by acomputer (and/or a processor within a computer); in an aspect, then,such code and/or instructions can be used to configure and/or adapt ageneral purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

A set of these instructions and/or code might be stored on anon-transitory computer-readable storage medium, such as thenon-transitory storage device(s) 925 described above. In some cases, thestorage medium might be incorporated within a computer system, such ascomputer system 900. In other embodiments, the storage medium might beseparate from a computer system (e.g., a removable medium, such as acompact disc), and/or provided in an installation package, such that thestorage medium can be used to program, configure, and/or adapt a generalpurpose computer with the instructions/code stored thereon. Theseinstructions might take the form of executable code, which is executableby the computer system 900 and/or might take the form of source and/orinstallable code, which, upon compilation and/or installation on thecomputer system 900 (e.g., using any of a variety of generally availablecompilers, installation programs, compression/decompression utilities,etc.), then takes the form of executable code.

It will be apparent to those skilled in the art that substantialvariations may be made in accordance with specific requirements. Forexample, customized hardware might also be used, and/or particularelements might be implemented in hardware, software (including portablesoftware, such as applets, etc.), or both. Further, connection to othercomputing devices such as network input/output devices may be employed.

As mentioned above, in one aspect, some embodiments may employ acomputer system (such as the computer system 900) to perform methods inaccordance with various embodiments of the invention. According to a setof embodiments, some or all of the procedures of such methods areperformed by the computer system 900 in response to processor 910executing one or more sequences of one or more instructions (which mightbe incorporated into the operating system 940 and/or other code, such asan application program 945) contained in the working memory 935. Suchinstructions may be read into the working memory 935 from anothercomputer-readable medium, such as one or more of the non-transitorystorage device(s) 925. Merely by way of example, execution of thesequences of instructions contained in the working memory 935 mightcause the processor(s) 910 to perform one or more procedures of themethods described herein.

The terms “machine-readable medium” and “computer-readable medium,” asused herein, refer to any medium that participates in providing datathat causes a machine to operate in a specific fashion. In an embodimentimplemented using the computer system 900, various computer-readablemedia might be involved in providing instructions/code to processor(s)910 for execution and/or might be used to store and/or carry suchinstructions/code. In many implementations, a computer-readable mediumis a physical and/or tangible storage medium. Such a medium may take theform of a non-volatile media or volatile media. Non-volatile mediainclude, for example, optical and/or magnetic disks, such as thenon-transitory storage device(s) 925. Volatile media include, withoutlimitation, dynamic memory, such as the working memory 935.

Common forms of physical and/or tangible computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, punchcards, papertape, any other physical medium with patternsof holes, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip orcartridge, or any other medium from which a computer can readinstructions and/or code.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to the processor(s) 910for execution. Merely by way of example, the instructions may initiallybe carried on a magnetic disk and/or optical disc of a remote computer.A remote computer might load the instructions into its dynamic memoryand send the instructions as signals over a transmission medium to bereceived and/or executed by the computer system 900.

The communications subsystem 930 (and/or components thereof) generallywill receive signals, and the bus 905 then might carry the signals(and/or the data, instructions, etc. carried by the signals) to theworking memory 935, from which the processor(s) 910 retrieves andexecutes the instructions. The instructions received by the workingmemory 935 may optionally be stored on a non-transitory storage device925 either before or after execution by the processor(s) 910.

It should further be understood that the components of computer system900 can be distributed across a network. For example, some processingmay be performed in one location using a first processor while otherprocessing may be performed by another processor remote from the firstprocessor. Other components of computer system 900 may be similarlydistributed.

The methods, systems, and devices discussed above are examples. Variousconfigurations may omit, substitute, or add various procedures orcomponents as appropriate. For instance, in alternative configurations,the methods may be performed in an order different from that described,and/or various stages may be added, omitted, and/or combined. Also,features described with respect to certain configurations may becombined in various other configurations. Different aspects and elementsof the configurations may be combined in a similar manner. Also,technology evolves and, thus, many of the elements are examples and donot limit the scope of the disclosure or claims.

Specific details are given in the description to provide a thoroughunderstanding of example configurations (including implementations).However, configurations may be practiced without these specific details.For example, well-known circuits, processes, algorithms, structures, andtechniques have been shown without unnecessary detail in order to avoidobscuring the configurations. This description provides exampleconfigurations only, and does not limit the scope, applicability, orconfigurations of the claims. Rather, the preceding description of theconfigurations will provide those skilled in the art with an enablingdescription for implementing described techniques. Various changes maybe made in the function and arrangement of elements without departingfrom the spirit or scope of the disclosure.

Also, configurations may be described as a process which is depicted asa flow diagram or block diagram. Although each may describe theoperations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be rearranged. A process may have additional steps notincluded in the figure. Furthermore, examples of the methods may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware, or microcode, the programcode or code segments to perform the necessary tasks may be stored in anon-transitory computer-readable medium such as a storage medium.Processors may perform the described tasks.

Having described several example configurations, various modifications,alternative constructions, and equivalents may be used without departingfrom the spirit of the disclosure. For example, the above elements maybe components of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the invention.Also, a number of steps may be undertaken before, during, or after theabove elements are considered. Accordingly, the above description doesnot bound the scope of the claims.

What is claimed is:
 1. A system for encrypting multiple televisionchannels, the system comprising: one or more processors; and a memorycommunicatively coupled with and readable by the one or more processorsand having stored therein processor-readable instructions which, whenexecuted by the one or more processors, cause the one or more processorsto: designate a first television channel of a plurality of televisionchannels to be protected via a first entitlement control message (ECM)using a first encryption scheme, wherein the plurality of televisionchannels are transmitted using a single transponder stream; designate asecond television channel of the plurality of television channels to beprotected via a second ECM encrypted using a second encryption schemewhile the first ECM of the first television channel of the plurality oftelevision channels is protected using the first encryption scheme,wherein the first ECM encrypted using the first encryption schemerequires more processing to decrypt than the second ECM encrypted usingthe second encryption scheme; cause the first ECM encrypted using thefirst encryption scheme and a second ECM encrypted using the secondencryption scheme to be transmitted to a plurality of televisionreceivers, wherein: data from the first ECM is used for descrambling ofthe first television channel by the plurality of television receivers,and data from the second ECM is used for descrambling of the secondtelevision channel by the plurality of television receivers: andperiodically rotate selection of a television channel from the pluralityof television channels of the single transponder stream for encryptionof the selected television channel's ECM using the first encryptionscheme, wherein: ECMs for each television channel of the plurality oftelevision channels are periodically encrypted with the first encryptionscheme and, at other times, encrypted using the second encryptionscheme; and at a given time, an ECM for only one channel of theplurality of television channels transmitted using the singletransponder stream is encrypted using the first encryption scheme andECMs for each other television channel of the plurality of televisionchannels of the single transponder scheme are encrypted using the secondencryption scheme.
 2. The system for encrypting multiple televisionchannels using multiple encryption schemes of claim 1, wherein theprocessor-readable instructions, when executed by the one or moreprocessors, cause the one or more processors to: cause the plurality ofchannels to be transmitted concurrently to a plurality of televisionreceivers using the single transponder stream, wherein: data from thefirst entitlement control message is required to descramble the firsttelevision channel; and data from the second entitlement control messageis required to concurrently descramble the second television channelduring a time period the first television channel is being descrambled.3. The system for encrypting multiple television channels using multipleencryption schemes of claim 1, wherein: at a given time, only onetelevision channel of the plurality of television channels transmittedconcurrently using the single transponder stream is protected using thefirst encryption scheme.
 4. The system for encrypting multipletelevision channels using multiple encryption schemes of claim 1,further comprising: a television receiver comprising a smartcard, thetelevision receiver configured to: decrypt, using the smartcard, thefirst entitlement control message from the first encryption scheme,wherein the television receiver is of the plurality of televisionreceivers; and decrypt, using the smartcard, the second entitlementcontrol message from the second encryption scheme.
 5. The system forencrypting multiple television channels using multiple encryptionschemes of claim 4, wherein: the smartcard decrypting the firstentitlement control message takes a longer period of time than thesmartcard decrypting the second entitlement control message.
 6. A methodfor encrypting multiple television channels, the method comprising:designating, by the television service provider system, a firsttelevision channel of a plurality of television channels to be protectedvia a first entitlement control message (ECM) using a first encryptionscheme, wherein the plurality of television channels are transmittedusing a single transponder stream; designating, by the televisionservice provider system, a second television channel of the plurality oftelevision channels to be protected via a second ECM encrypted using asecond encryption scheme while the first ECM of the first televisionchannel of the plurality of television channels is protected using thefirst encryption scheme; transmitting, by the television serviceprovider system, the first entitlement control message encrypted usingthe first encryption scheme and a second entitlement control messageencrypted using the second encryption scheme to a plurality oftelevision receivers, wherein: data from the first entitlement controlmessage is used for descrambling of the first television channel by theplurality of television receivers, and data from the second entitlementcontrol message is used for descrambling of the second televisionchannel by the plurality of television receivers; and rotating, by thetelevision service provider system, selection of a television channelfrom the plurality of television channels of the single transponderstream for encryption of the selected television channel's ECM using thefirst encryption scheme, wherein: ECMs for each television channel ofthe plurality of television channels are periodically encrypted with thefirst encryption scheme and, at other times, encrypted using the secondencryption scheme; and at a given time, an ECM for only one channel ofthe plurality of television channels transmitted using the singletransponder stream is encrypted using the first encryption scheme andECMs for each other television channel of the plurality of televisionchannels of the single transponder scheme are encrypted using the secondencryption scheme.
 7. The method for encrypting multiple televisionchannels using multiple encryption schemes of claim 6, furthercomprising: transmitting, by the television service provider system, theplurality of channels concurrently to a plurality of televisionreceivers using the single transponder stream, wherein: data from thefirst entitlement control message is required to descramble the firsttelevision channel; and data from the second entitlement control messageis required to concurrently descramble the second television channelduring a time period the first television channel is being descrambled.8. The method for encrypting multiple television channels using multipleencryption schemes of claim 6, further comprising: decrypting, by asmartcard of a television receiver, the first entitlement controlmessage from the first encryption scheme, wherein the televisionreceiver is of the plurality of television receivers; and decrypting, bythe smartcard of the television receiver, the second entitlement controlmessage from the second encryption scheme.
 9. The method for encryptingmultiple television channels using multiple encryption schemes of claim8, wherein: decrypting, by the smartcard of the television receiver, thefirst entitlement control message takes a longer period of time thandecrypting the second entitlement control message.
 10. A non-transitoryprocessor-readable medium for encrypting multiple television channels,comprising processor-readable instructions configured to cause one ormore processors to: designate a first television channel of a pluralityof television channels to be protected via a first entitlement controlmessage (ECM) using a first encryption scheme, wherein the plurality oftelevision channels are transmitted using a single transponder stream;designate a second television channel of the plurality of televisionchannels to be protected via a second (ECM) encrypted using a secondencryption scheme while the first television channel of the plurality oftelevision channels is protected using the first encryption scheme,wherein the first (ECM) encrypted using the first encryption schemerequires more processing to decrypt than the second (ECM) encryptedusing the second encryption scheme; cause the first (ECM) encryptedusing the first encryption scheme and a second (ECM) encrypted using thesecond encryption scheme to be transmitted to a plurality of televisionreceivers, wherein: data from the first (ECM) is used for descramblingof the first television channel by the plurality of televisionreceivers, and data from the second (ECM) is used for descrambling ofthe second television channel by the plurality of television receivers;and periodically rotate selection of a television channel from theplurality of television channels of the single transponder stream forencryption of the selected television channel's ECM using the firstencryption scheme, wherein: ECMs for each television channel of theplurality of television channels are periodically encrypted with thefirst encryption scheme and, at other times, encrypted using the secondencryption scheme; and at a given time, an ECM for only one channel ofthe plurality of television channels transmitted using the singletransponder stream is encrypted using the first encryption scheme andECMs for each other television channel of the plurality of televisionchannels of the single transponder scheme are encrypted using the secondencryption scheme.
 11. The non-transitory computer-readable medium forencrypting multiple television channels using multiple encryptionschemes of claim 10, wherein the processor-readable instructions, whenexecuted by the one or more processors, cause the one or more processorsto: cause the plurality of channels to be transmitted concurrently to aplurality of television receivers using the single transponder stream,wherein: data from the first entitlement control message is required todescramble the first television channel; and data from the secondentitlement control message is required to concurrently descramble thesecond television channel during a time period the first televisionchannel is being descrambled.